The chemical composition, synthesis and organization of glycolipids have been compared between transformed and non-transformed cells. The results of these studies, supported by this grant, indicated that: blocked synthesis and associated precursor accumulation, and loss of glycolipid crypticity occurred associated with transformation. Furthermore, recent studies indicated that precursor accumulation may relate to the antigenicity change of tumor cells. Based on these results, the following studies are proposed: 1) The major study is focused on the correlation of glycolipid accumulation in transformed cells and antigenicity and immunogenicity change of tumor cells. "Paragloboside" of NILpy tumor and ganglio-N-triosylceramide (asialo GM2) of 3T3KiMSV tumor will be used as model immunogens. Glycolipids of other tumor systems which would show a marked change in structure or in crypticity as compared to normal cells will be investigated as immunogen. 2) The change in glycolipid structure of tumor cells will be studied by a combination of enzymatic degradation and mass fragmentography on both chemical ionization and electron impact methods. The detergent-solubilized, surface-labeled carbohydrates will be trapped by anti-glycolipid antibody followed by separation into glycoprotein and glycolipid. This approach will evaluate whether or not the change that occurred in glycolipid can also be observable in glycoprotein. 3) The induced change of growth regulation by addition of exogenous glycolipids or by chemically modified analogs will be studied. The addition of glycolipids (or its analog) may change membrane glycolipid profile and may effect glycolipid metabolism, thus may alter transformed phenotype.